Self-assembled, highly-lithiophilic and well-aligned biomass engineered MXene paper enables dendrite-free lithium metal anode in carbonate-based electrolyte

Lithium metal anode is the ideal candidate for high-energy–density rechargeable batteries. However, uncontrolled dendrite growth hampers its commercialization. Herein, a dendrite-free composite Li metal anode is realized by a flexible, freestanding, well-aligned and highly-lithiophilic MXene paper designed by a facile electrostatic self-assembly of the exfoliated MXene nanosheets and natural polysaccharide-chitosan ([email protected]). The [email protected] paper gets a well-aligned layered-3D structure with a micro-crumpled surface that can effectively decrease the local current density, guide even Li plating and suppress dendritic Li growth. More importantly, surface-adsorbed chitosan endows enhanced lithiophilicity for MXene substrate and thus reduces the Li nucleation overpotential, which is confirmed by the density functional theory calculations. Abundant lithiophilic groups on [email protected] surface provide high-concentration Li+ anchoring site promoting Li nucleation and laterally inducing uniform Li deposition, which effectively avoids the formation of dendritic Li. As a result, the [email protected] anode with a dendrite-free Li morphology shows a significantly improved cycling life in commercial carbonate-based electrolyte. When coupled with LiNi0.8Co0.1Mn0.1O2 cathode, the full cell exhibits a low capacity decay and steady ultrahigh Coulombic efficiency of 99.6% at a current density of 5C. These findings develop a new approach for designing high-performance metal-based rechargeable batteries.